Geological sequestration of carbon dioxide (CO2) is one of various developing technologies that can be used to reduce the emission of CO2 and mitigate greenhouse effects. This technology, which is also named CCS (Carbon Capture and Storage), captures the CO2 from production sources like power plants (coal or gas fired) and transfers it to sink or storage sites (or geologic unit). Geological CO2 storage sites can include hydrocarbon reservoirs, deep saline reservoirs and coal bed formations. The CO2 can then be injected, preferably in the supercritical phase, into the underground sites for long term storage. However, it is possible that the sequestrated CO2 could leak back into the atmosphere through some leakage paths, leading to negate the benefits of geologic CO2 sequestration.
Geological sequestration of natural gas is also possible. Natural gas is usually produced in southern states and delivered to northern states for storage in underground reservoirs during the warmer months for later use during the colder winter months. The natural gas is stored underground by injecting the gas at pressures higher than the native pressure of the reservoir (or storage site) for later extraction and use. One example of this is the SoCal Gas Site at Porter Ranch, Calif. However, it is possible that the stored natural gas could leak out of the reservoir, potentially leading to economic hardship and environmental problems.